Six pairs of phenylpropanoid enantiomers from Cinnamomum mollifolium

• Published in: Phytochemistry (Oxford) 2022-11, Vol.203, p.113348-113348, Article 113348
• Main Authors: Wen, Yan, Rao, Li, Xu, Fan, Li, Yang, Luo, Yong-Xin, Gong, Xu, Wu, Ri-Hui, Zhang, Chuan-Rui, Gan, Li-She
• Format: Article
• Language: English
• Subjects: Absolute configuration; Cinnamomum mollifolium H. W. Li; Lauraceae; Mollifoline; Phenylpropanoid
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2022.113348

Six pairs of undescribed phenylglycerol benzoate enantiomers, (±)-mollifolines A−F, which can also be categorized into three two-pairs of epimers, were isolated from Cinnamomum mollifolium H. W. Li (Lauraceae). The relative configurations (threo or erythro) of the epimers were determined by conformational searching of the lowest energy conformers and analyses of the relationship between the dihedral angle of H-7'─C-7'─C-8'─H-8′ and the 3JH-7', H-8' coupling constant according to the Karplus equation. Furthermore, intramolecular hydrogen bonds were proved to play an important role in stabilizing the lowest conformations by using reduced density gradient (RDG) method for noncovalent interactions. Chiral resolutions of these enantiomer pairs were accomplished by immobilized polysaccharide derivative-based chiral HPLC columns. Absolute configurations of the 12 optically pure isomers were finally determined by quantum chemical time-dependent density functional theory (TDDFT) calculations of their electronic circular dichroism (ECD) spectra. Six pairs of undescribed phenylglycerol benzoate enantiomers, (±)-mollifolines A−F, were isolated from Cinnamomum mollifolium H. W. Li (Lauraceae) and later were separated on chiral HPLC columns. Computer aided conformational analysis, reduced density gradient method, and TDDFT calculation of ECD spectrum were applied to determine the relative and absolute configurations. [Display omitted] •Six pairs of undescribed phenylglycerol benzoate enantiomers were isolated from Cinnamomum mollifolium.•Chiral resolutions of these enantiomer pairs were accomplished.•Computer aided conformational analyses and RDG method were applied to determine the relative configurations.•The absolute configurations were determined by quantum chemical calculations of their ECD spectra.